Page:Supplement to the fourth, fifth, and sixth editions of the Encyclopaedia Britannica - with preliminary dissertations on the history of the sciences - illustrated by engravings (IA gri 33125011196181).pdf/172

118 1. I have already taken notice of Malebranche’s comments on the Cartesian doctrine concerning the sensible, or, as they are now more commonly called, the secondary qualities of matter. The same fulness and happiness of illustration are everywhere else to be found in his elucidations of his master’s system; to the popularity of which he certainly contributed greatly by the liveliness of his fancy, and the charms of his composition. Even in this part of his writings, he always preserves the air of an original thinker; and, while pursuing the same path with Descartes, seems rather to have accidentally struck into it from his own casual choice, than to have selected it out of any deference for the judgment of another. Perhaps it may be doubted, if it is not on such occasions, that the inventive powers of his genius, by being somewhat restrained and guided in their aim, are most vigorously and most usefully displayed.

In confirmation of this last remark, I shall only mention, by way of examples, his comments on the Cartesian theory of Vision,—more especially on that part of it which relates to our experimental estimates of the distances and magnitudes of objects; and his admirable illustration of the errors to which we are liable from the illusions of sense, of imagination, and of the passions. In his physiological reveries on the union of soul and body, he wanders, like his master, in the dark, from the total want of facts as a foundation for his reasonings; but even here his genius has had no inconsiderable influence on the inquiries of later writers. The fundamental principle of Hartley is most explicitly stated in The Search after Truth; as well as a hypothesis concerning the nature of habits, which, rash and unwarranted as it must now appear to every novice in science, was not thought unworthy of adoption in The Essay on Human Understanding.

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